Q: Does regular exercise improve survival after cancer, or does it just seem to prevent cancer?
A: We need long-term studies involving lots of people and a wide range of cancer types before we can answer that question confidently. The good news is that research is in progress. So far, most studies have looked at breast and colorectal cancer survivors. Evidence is good that regular exercise can improve quality of life, including energy, emotional health and strength for daily activities, such as carrying groceries and climbing up a flight of stairs. Studies are beginning to show the same kinds of changes in hormones and growth factors that seem to lower risk of cancer also occurring in cancer survivors with regular exercise, which is a hopeful sign. Research does show that those who avoid excess weight gain seem more likely to survive longer, and exercise is a key part of weight control. Several studies now show that survival rates are higher for those colon and breast cancer survivors who exercised more than those who exercised little. But these are not randomized controlled studies, and do not show cause-and-effect. Nevertheless, as long as you discuss exercise plans with your doctor to be sure there are no special cautions, exercising regularly may be a good move.

Q: Can healthy eating help prevent damage to vision from macular degeneration?
A: Age-related macular degeneration (AMD) is still not fully understood, but experts believe it involves damage to the retina of the eye by highly reactive free radicals. The large Age-Related Eye Disease Study showed that high doses of antioxidant supplements might slow the progression from early to late AMD. Research does not show that early supplementation prevents AMD, however. A large study of over 4,000 people suggests that we can probably lower risk of AMD by about 35 percent with a diet that supplies antioxidant nutrients. The key parts of such a daily diet are: six or more servings of vegetables and fruits (with at least 1 ? cups of dark green and 1 cup of orange vegetables per week), three or more servings of whole grains, 4 to 6 ounces of meat, poultry or seafood (or bean equivalents; about 2 to 3 cups), 5 to 7 teaspoons of oils like canola and olive, and about 1 ounce of nuts. This study found that diets high in several antioxidants seem to lower AMD risk more than high amounts of any single antioxidant. Eating fish at least twice a week may also substantially reduce AMD risk. Other studies have found that overdoing total fat consumption, particularly with lots of polyunsaturated fat, may increase AMD risk.

Q: What are soy nuts? Are they healthful choices?
A: Soy nuts are roasted whole soybeans. They may be dry-roasted or oil-roasted. Soy nuts are available plain, salted, or in a variety of other flavors. A quarter-cup serving contains about 194 calories, just a little less than the same portion of peanuts. Like many other soy foods, they are not low-fat, but the fat is almost all unsaturated; saturated fat content is very low. That quarter-cup provides 17 grams of soy protein, a major portion of the 25 grams that some studies have shown helps lower blood cholesterol. Unsalted soy nuts contain only a trace of sodium; salted versions remain reasonable as long as your portions are controlled, with about 70 to 120 milligrams of sodium in a quarter-cup.